JPH024073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating head slider used in magnetic disk devices, etc., and particularly relates to a slider shape that utilizes the suction force generated by negative pressure, which has been actively developed recently. It is.

As is well known, the mainstream of floating head sliders for conventional magnetic disk devices is a tapered flat type elongated planar slider that utilizes only positive pressure and is suitable as a low-load, microfloating head with excellent dynamic followability. However, since the air film rigidity of this positive pressure slider is approximately proportional to the pressing force applied to the slider, there is a certain limit to increasing the rigidity in a low load head. From this perspective, recently,
In addition to the positive pressure, a reverse step surface or a diverging surface is provided within the slider surface to generate negative pressure.
A so-called negative pressure floating head slider (hereinafter referred to as a negative pressure slider), which absorbs a portion of the load applied to the floating head by the suction force, is being actively developed. As is clear from its flotation mechanism, negative pressure sliders have the following advantages compared to conventional positive pressure sliders: 1) The slider air film rigidity can be increased even with a small load, 2) The load setting range can be widened.
3) The slider has extremely good lift characteristics with respect to the media circumferential speed, making it suitable for CSS such as plating media and sputtering media. For this reason, negative pressure sliders of various shapes have been proposed. Regarding a negative pressure slider whose positive pressure generating surface is constituted by a tapered flat surface, a shape as shown in FIGS. 1A and 1B or 2A and 2B has been proposed. Note that in each figure, a shows a plan view, and b shows a front view. In the conventional structure shown in FIGS. 1a and 1b, there is a positive pressure generating surface 1 and a cross rail surface 3 coplanar with the positive pressure generating surface 1. A reverse step surface is formed by the recessed portion 2 surrounded by the positive pressure generating surface 1 and the cross rail surface 3, and that portion becomes a negative pressure generating surface. In addition, in the case of this shape, an auxiliary groove 4 that is deeply ground by machining or the like is required at the tapered portion of the positive pressure generating surface 1 in order to prevent pressure from increasing and set the angle of attack of the slider to an appropriate value. be.
Such conventional negative pressure sliders have certain drawbacks. In other words, when considering performing contact start/stop (hereinafter referred to as CSS) with the recording medium, unlike the case of the tapered flat type positive pressure slider that has been put into practical use so far,
The cross rail surface 3 will come into contact with the medium.
Therefore, the sharp end surface on the air inflow side, which is composed of the cross rail surface 3 and the auxiliary groove 4, comes into contact with the medium due to the stick-slip phenomenon of the slider during CSS, thereby damaging the medium surface. This is a major cause of head crash during CSS of the negative pressure slider. Another drawback is that the head manufacturing process requires not only the ion etching method based on photolithography technology, but also machining or electric discharge machining for machining the auxiliary grooves 4. This is by no means a good idea considering the manufacturing cost of the negative pressure slider.

On the other hand, in the conventional shape example shown in FIG. 2, these 20 drawbacks are skillfully solved.
However, in the case of this shape, especially when the taper section is short, the negative pressure generating surface 2a becomes an inverted tapered flat surface, which meets the design conditions basically required for a negative pressure slider. Considering the condition that "in order to obtain a high-rigidity slider with a low load, sufficient negative pressure must be generated," this method has the disadvantage that the negative pressure generation efficiency is extremely low compared to a reverse step surface. Therefore, in order to improve the shortcomings of these 20 conventional structural examples, it is necessary to eliminate the sharp end surface formed by the cross rail surface 3 and the auxiliary groove 4 from the viewpoint of CSS, and to ensure that the negative pressure generating surface is negative. It is necessary to consider a negative pressure slider shape that has a surface shape with good pressure generation efficiency.

It is an object of the present invention to provide a negative pressure slider whose positive pressure generating surface is a tapered flat surface or a stepped surface, to eliminate the above-mentioned drawbacks of the negative pressure sliders proposed so far, and to improve the efficiency of negative pressure generation. The object of the present invention is to provide a low-cost negative pressure slider shape that has excellent processability and productivity.

In the negative pressure slider of the present invention, the tapered portion of the tapered flat surface that is the positive pressure generating surface is shortened, and the inflow end of the negative pressure generating surface is moved from the terminal position of the tapered portion of the positive pressure generating surface to the opposite step surface. By forming it into a shape, the above object is achieved.

According to the negative pressure slider of the present invention, since the negative pressure generating surface is a reverse step surface, unlike the conventional structure, the negative pressure generating efficiency is extremely high, and the negative pressure does not depend on the minimum floating amount. It becomes constant. In addition, since there is no cross rail surface, when performing CSS with the recording medium, it is exactly the same as the positive pressure slider that has been put into practical use so far, and the recording medium will not be particularly damaged. Further, according to this shape, there is no need to provide an auxiliary groove by machining or the like at the tapered portion in order to prevent the slider angle of attack from increasing as in the conventional case. Therefore, since the slider can be processed only by ion etching using photolithography after polishing the slider surface, it is possible to easily obtain a negative pressure slider with good flotation characteristics at low cost.

The present invention will be explained in detail below using the drawings.

FIGS. 3a and 3b are a plan view and a front view, respectively, showing the first embodiment of the present invention. As shown in the figure, the negative pressure slider of the present invention has a negative pressure generating surface 1b that constitutes a positive pressure generating surface and a tapered portion of the left side taper portion in the figure is made extremely short.
It is characterized in that the inflow end of b is formed from the terminal end of the tapered surface. Therefore, as is clear from FIG. 3b, the negative pressure generating surface 2b becomes, so to speak, a reverse step surface tapered at the front. In the case of such a reverse step surface, the generation efficiency of negative pressure per unit area is much higher than that of the previously proposed reverse tapered flat surface shape shown in FIG. This fact can be obtained by solving the modified Reynolds equation under the required boundary conditions, taking into account the mean free path of air based on the air film lubrication theory, which well represents the static levitation characteristics of the slider. In other words, the negative pressure is about twice as large as that of the negative pressure slider of the conventionally proposed shape shown in FIG. 2, and a slider with lower load and higher rigidity can be obtained. Furthermore, considering the design requirements of the negative pressure slider, in order to increase the stiffness of the air film, the negative pressure must be a constant value independent of the slider's minimum floating amount, but this is also the same as above. By solving the equation numerically, it can be proven that the negative pressure slider of the present invention has better characteristics. In other words, if the negative pressure generating surface is a reverse tapered flat slider, for example, the minimum floating amount is from 0.3μm.
Compared to the negative pressure that increases by about 10% when changing to 0.1 μm, in the case of the negative pressure slider of the present invention, it only changes by about 2 to 3% under the same flotation conditions, and it almost depends on the minimum flotation amount. I will not do it. This shows that the amount of change in negative pressure is smaller than the amount of change in positive buoyancy force with respect to changes in levitation amount,
This means that the stiffness of the air film as a whole increases accordingly.

On the other hand, when looking at the negative pressure slider of this embodiment from the viewpoint of CSS at the time of starting and stopping the medium, which greatly affects the reliability of the floating head, it is different from the conventional shape shown in Fig. 1 because it forms a negative pressure generating surface. Because there is no so-called cross rail surface, it is exactly the same as the twin-barrel tapered flat positive pressure slider that has already been put into practical use and has a proven track record in the boundary lubrication area when the slider is stationary above the recording medium or at low speeds. It becomes the type of. Therefore, if we consider the flying characteristics of a negative pressure slider relative to the media peripheral speed, which is better than that of a positive pressure slider, CSS
This also greatly reduces the risk of scratches on the recording medium.

Furthermore, when looking at the manufacturing method of a specific negative pressure slider that is important in practice, it can be seen that the shape is improved over the conventional shape. In other words, in the case of this shape, first the entire slider surface is polished into a tapered flat shape, and then the negative pressure generating surface 2b is processed by an ion etching method or a sandblasting method based on photolithography technology, and there is no need for any mechanical processing. No auxiliary groove is required. Therefore, it is possible to easily obtain a negative pressure slider based on an extremely efficient, low-cost, and inexpensive batch manufacturing process.

FIGS. 4a and 4b are a plan view and a front view, respectively, showing a second embodiment of the present invention. In this shape, the positive pressure generating surface 1c and its left-hand step form a step bearing surface. The negative pressure generating surface 2c is a so-called reverse step bearing surface, and the effects in this case are exactly the same as in the first embodiment.

FIGS. 5a and 5b and 6a and 6b are diagrams showing third and fourth embodiments of the present invention. In this example, the negative pressure generating surfaces 2d and 2e are formed as reverse tapered surfaces. Such a shape cannot be processed by methods such as ion etching, and must be processed by machining. It is clear that the effects in this case are also exactly the same as those in the first and second embodiments.

As described above in detail about the present invention, the negative pressure slider of the present invention shortens the tapered portion or step surface length of the positive pressure generating surface, and forms the inflow end of the negative pressure generating surface from the end position of the taper or step. By doing so, it is possible to provide a low-cost negative pressure slider that does not have a cross rail surface like the conventional one and has a higher negative pressure generation efficiency than the conventional one.

Note that any modification may be made without departing from the spirit of the present invention; for example, the positive pressure generating surface may be a tapered crown slider without any problem.
It is clear that the description of the above embodiments is not intended to limit the scope of the invention in any way.

[Brief explanation of drawings]

Figures 1a and b are plan and front views showing a conventional negative pressure slider having a cross rail surface and an auxiliary groove, and Figures 2a and b are views in which the inflow end of the negative pressure generating surface is formed in the middle of the tapered part. In the plan view, front view, and Figures 3a and 3b showing a conventional negative pressure slider, the positive pressure generating surface is formed of a tapered flat surface, and the inflow end of the reverse step-shaped negative pressure generating surface is the terminal end of the tapered part. FIGS. 4a and 4b show a plan view and a front view showing the first embodiment of the present invention formed from Figures 5a and 5b show a second embodiment of the present invention in which the end is formed from the end of a step surface, and the positive pressure generating surface is formed from a tapered flat surface and is formed from the end of the tapered part. A plan view and a front view showing a third embodiment of the present invention in which the negative pressure generating surface has a reverse tapered shape, and FIGS. 6a and 6b show a positive pressure generating surface having a step bearing surface and a step surface. FIG. 6 is a plan view and a front view showing a fourth embodiment of the present invention, in which the negative pressure generating surface formed from the terminal end of the cylinder has an inversely tapered shape. In the figure, 1, 1a, 1b, 1c, 1d, 1
e is a positive pressure generating surface, 2, 2a, 2b, 2c, 2d,
2e indicates a negative pressure generating surface, 3 indicates a cross rail surface, and 4 indicates an auxiliary groove.

Claims (1)

[Claims] 1. In a negative pressure floating head slider having a positive pressure generating surface having a tapered surface or a step surface at the air inflow end, and a negative pressure generating surface having a tapered surface or a step surface having an inclination in the opposite direction to the tapered surface,
A floating head slider utilizing negative pressure, characterized in that the inflow end of the negative pressure generating surface of the reverse taper or reverse step is formed from the terminal end of the taper or step of the positive pressure generating surface.